Possible use of spin-vortex-induced loop currents as qubits: A numerical simulation for two-qubit systemPossible use of spin-vortex-induced loop currents as qubits: A numerical simulation for two-qubit systemAA11461984

We propose new qubits; they are nano-sized persistent loop currents called, the spin-vortex-induced loop currents (SVILCs), predicted to exist in hole doped cuprate superconductors in one of the proposed mechanisms of the cuprate superconductivity. In the SVILC theory for the cuprate superconductivity, the superconducting state arises when the network of SVILCs generates a macroscopic current as a collection of the loop currents.The predicted SVILC has a number of properties that are suitable for qubits: each SVILC is characterized by topological winding number, thus, expected to be robust against environmental perturbations; because of the smallness of their size, they can be assembled into a large qubit-number system in a small space.Energy levels of different current patterns of the SVILC system are split by an external inhomogeneous magnetic field, and they are used as qubit states. The quantum gate control is achieved by the Rabi oscillation using electric dipole transitions. We have calculated the transition dipole moments between different SVILC qubit states. Some of the calculated values are relatively large, around 10−3010−30 C m. We have also performed a numerical simulation for the Glover’s search algorithm using the two-qubit SVILC system. The search completes in a nanosecond order using the electromagnetic field with electric field amplitude 105 V/m. The present results indicate the quantum gate control capability of the SVILC qubits, and suggest the potentiality to satisfy DiVincenzo’s criteria for quantum computers.